Magnetic interfaces between spin waves and nitrogen-vacancy centers

Spin waves are promising information carriers in next-generation computers. Interfacing them with quantum emitters could enable to tailor their properties in analogy with the modifications of light propagation in dense atomic media.
In this work, we provide a full quantum theory of spin wave-quantum emitter interfaces, focusing on an ensemble of nitrogen-vacancy centres in diamond (NVs) in the vicinity of an Yttrium-Iron-Garnet thin film. We show strong and tuneable modification of spin wave propagation induced by the back-action of the NVs including, among others, full suppression or enhancement of their propagation length along certain propagation directions. Furthermore, we show the possibility of probing spin waves mechanically through the measurement of the spin-wave induced thermal forces on nearby NVs. In addition, we use our theory to compute: (i) the spin-wave-induced modification of the NV lifetimes T1 and T2; (ii) the spin-wave-induced interaction between different NVs within an ensemble; (iii) the NV-induced modification of the magnetic field power spectral density outside the film.
Our results are measurable by current experiments and generalizable to other quantum emitters and magnetic structures, providing a toolbox toward magnetic hybrid quantum technologies.